14 FODDER AND PASTURE PLANTS. 
(Fig. 5, St.) acts differently in different plants. In beans it grows 
in length and lifts the cotyledons (Fig. 5, Cot.), which gradually 
become flat and thin, above the ground. In peas it is short, and the 
cotyledons remain hidden in the soil for a long time, enclosed within 
the seed coat. 5 
Root system: Leguminous plants are annual, biennial or per- 
ennial. When annual, like Crimson Clover, or biennial, like Sweet 
Clover, the primary root of the embryo always develops into a tap- 
root. When they are perennial, a taproot may be found, or the under- 
ground system may consist of a rootstock, from which secondary 
roots are developed. With a rootstock the system is generally 
shallow and the plants depend on the surface soil for their food. A 
taproot usually penetrates to a considerable depth and the plant 
gets much of its food from the subsoil. Both secondary roots and 
taproots are characterized by small tubercles or clusters of nodules. 
The significance of these is discussed on page 18. 
Stems: The stems of leguminous plants are erect or ascending 
asarule. Only in a few cases, as in White Clover, are they creeping 
and able to develop secondary roots from their joints. Plants of 
this type form more or less spreading mats, in which individuals are 
difficult to recognize. The same is often the case when the stems, 
as in Flat Pea, develop from a spreading and extensively branched 
rootstock. In some species and genera, as in Flat Pea and Vetches, 
the stems are weak and are kept from falling to the ground by special 
organs on the leaves, called tendrils (see below). 
Leaves: The leaves of leguminous plants are compound; that 
is, each leaf consists of a number of leaflets each completely separated 
from the others. The type—a leaf consisting of a number of pairs 
of leaflets and ending with an odd one—is that of Sainfoin (Plate 23). 
All other kinds are mere modifications of this type. Thus, when the 
leaflets are only three, as in Red Clover, Alfalfa, Sweet Clover and 
others, the well-known trifoliate leaf is obtained. In other species, 
such as the vetches (Plates 24 and 25) and Flat Pea, the blades of 
the upper leaflets are not developed; only their ribs remain and they 
are transformed into tendrils, the function of which is to support the 
weak stems. 
Everybody knows that the plants in a field of peas or vetches 
are sometimes so firmly tied together, when the stand is dense, that 
to pull those at the end of a long row will move the plants at the other 
end. This is because the tendrils wind about the stems and branches 
of neighboring plants and bind them together. These tendrils are 
